#!/usr/bin/perl

#  unipng2hex - program to turn a .png glyph matrix into a
#               GNU Unifont hex glyph set of 256 characters
#
#  Synopsis: unipng2hex [-i in_file.png] [-o out_file.hex] [-w]
#
#
#  Author: Paul Hardy, unifoundry <at> unifoundry.com, December 2007
#
#  Perl conversion: Andrew Miller, August 2013
#
#
#   Copyright (C) 2007-2008 Paul Hardy
#
#   This program is free software: you can redistribute it and/or modify
#   it under the terms of the GNU General Public License as published by
#   the Free Software Foundation, either version 2 of the License, or
#   (at your option) any later version.
#
#   This program is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#   GNU General Public License for more details.
#
#   You should have received a copy of the GNU General Public License
#   along with this program.  If not, see <http://www.gnu.org/licenses/>.

use Getopt::Long;
use GD qw (:DEFAULT :cmp);

$result = GetOptions (
	"help|?",
	"input|i=s" => \$input,
	"output|o=s" => \$output,
	"width|w=i" => \$minwidth
);

if ($opt_help) {
	print << "END" or die ("Cannot print to stdout.\n");

Turn a .png glyph matrix into a GNU Unifont hex glyph set of 256 characters

Syntax:

   unipng2hex -i <Input_File> [-o <Output_File>] [-w <width>]

   -i, --input               the input PNG file
   -o, --output              the output hex file (write to STDOUT if not
                             specified)
   -w, --width               the minimum width of the output glyphs - valid
                             values are 16, 24 and 32 (default is no minimum
                             width)
   -?, --help                display this help and exit


Example:

   unipng2hex -i u83.png -o u83.hex
END
	exit ()
}

if (not $input) {
	die ("No input file specified\n")
}

#if (not $output) {
#	die ("No output file specified\n")
#}

GD::Image->trueColor (1);
$im = new GD::Image ("$input") or die ("Cannot open image.\n");

if ($im->isTrueColor ()) {
	$im->trueColorToPalette ();
}

# Disable transparency if it has been set
$im->transparent (-1);

$black = $im->colorClosest (0, 0, 0);
$white = $im->colorClosest (255, 255, 255);

# Exit if black and white are not in the image's palette
if ($white == -1 || $black == -1) {
	die ("Invalid image - colors do not match\n");
} else {
	($black_red, $black_green, $black_blue) = $im->rgb ($black);
	($white_red, $white_green, $white_blue) = $im->rgb ($white);
}

($imagewidth, $imageheight) = $im->getBounds();

$charxoffset = 4;
$gridxoffset = 48;
$gridyoffset = 32;

$boxsize = ($imagewidth - $gridxoffset) / 16;

if ($boxsize == 32) {
	# try to determine if charheight is 16 or 24 by examining grid
	$pixel = $im->getPixel ($imagewidth - 1, $imageheight - 5);

	if ($im->rgb ($pixel) == ($black_red, $black_green, $black_blue)) {
		$charyoffset = 7;
		$charheight = 16;
		$charmaxwidth = 3;
	} elsif ($im->rgb ($pixel) == ($white_red, $white_green, $white_blue)) {
		$charyoffset = 7;
		$charheight = 16;
		$charmaxwidth = 3;
#
#		Use the settings below for a height of 24 pixels in the future;
#		for now, hard code glyph height to 16 pixels.
#		$charyoffset = 4;
#		$charheight = 24;
#		$charmaxwidth = 3;
	} else {
		die ("Cannot determine font height\n")
	}
} elsif ($boxsize == 40) {
	$charyoffset = 4;
	$charheight = 32;
	$charmaxwidth = 4;
} else {
	die ("Invalid image - incorrect size\n")
}

if ($minwidth) {
	if ($charheight == 16 || $charheight == 24) {
		if (!($minwidth == 16 || $minwidth == 24)) {
			die ("invalid width\n");
		}
	} elsif ($charheight == 32) {
		if (!($minwidth == 16 || $minwidth == 24 || $minwidth == 32)) {
			die ("Invalid width\n");
		}
	}

	$minwidth /= 8;
}

# Build an array of single digit hex character images
for ($count = 0; $count < 16; $count++) {
	$digit = new GD::Image (8, 16, 0);
	$black = $digit->colorAllocate ($black_red, $black_green, $black_blue);
	$white = $digit->colorAllocate ($white_red, $white_green, $white_blue);

	$digit->fill (0, 0, $white);

	$digit->string (gdLargeFont, 0, 0, sprintf ('%X', $count), $black);

	push (@digits, $digit);
}

$codepoint = 0;

# Get plane
for ($d = 0; $d < 2; $d++) {
	$c = new GD::Image (8, 16);
	$c->copy ($im, 0, 0, 24 + ($d * 8), 9, 8, 16);

	for ($count = 0; $count < 16; $count++) {
		if (!($c->compare ($digits[$count]) & GD_CMP_IMAGE)) {
			$codepoint = ($codepoint << 4) + $count;
		}
	}
}

# Get page
for ($d = 0; $d < 3; $d++) {
	$c = new GD::Image (8, 16);
	$c->copy ($im, 0, 0, (($boxsize - 24) / 2) + $gridxoffset + ($d * 8), 9, 8, 16);

	for ($count = 0; $count < 16; $count++) {
		if (!($c->compare ($digits[$count]) & GD_CMP_IMAGE)) {
			$codepoint = ($codepoint << 4) + $count;
		}
	}
}

# Calculate the first codepoint and it's display width
$codepoint = ($codepoint << 4);
$display_width = $codepoint > 0xFFFF ? 6 : 4;

if ($output) {
	open (HEXFILE, ">$output") or die ("Cannot save hex file.\n");
} else {
	*HEXFILE = *STDOUT;
}
binmode HEXFILE;

for ($col = 0; $col < 16; $col++) {
	for ($row = 0; $row < 16; $row++) {
		# Calculate glyph width
		$charwidth = 0;

		for ($count = 0; $count < $charmaxwidth; $count++) {
			$c = new GD::Image (8, $charheight, 0);
			$c->copy ($im, 0, 0, ($col * $boxsize) + ($count * 8) + $gridxoffset + $charxoffset, ($row * $boxsize) + $gridyoffset + $charyoffset, 8, $charheight);

			if ($c->colorsTotal > 1 || $c->colorExact ($white_red, $white_green, $white_blue) == -1) {
				$charwidth = $count + 1
			}
		}

		# Force glyphs to minimum width if minwidth is set
		if ($charwidth < $minwidth) {
			$charwidth = $minwidth;
		}

		if ($charwidth != 0) {
			$char = sprintf ("%0*X:", $display_width, $codepoint);

			# Loop through the glyph and build up it's hex representation
			for ($j = 0; $j < $charheight; $j++) {
				$line = 0;

				for ($i = 0; $i < $charwidth * 8; $i++) {
					$bit = $im->getPixel (($col * $boxsize)+ $i + $gridxoffset + $charxoffset, ($row * $boxsize) + $j + $gridyoffset + $charyoffset) == $black ? 1 : 0;

					$line = ($line << 1) + $bit;
				}

				$char = $char . sprintf ("%0*X", $charwidth * 2, $line);
			}

			print HEXFILE "$char\n" or die ("Cannot print to hex file.\n");
		}

		$codepoint += 1;
	}
}

# Only close HEXFILE if it isn't mapped to STDOUT.
if ($output) {
	close HEXFILE or die ("Cannot properly close hex file.\n");
}